The concept of gravity casting lead or lead alloy parts is well known in the art. One of the problems in the art is the formation of voids or fissures in the cast product even though the mold surface is smooth and free of obstructions. In order to avoid formation of voids or fissures in the cast part the mold surfaces are periodically sprayed with a solution of sodium silicate and finely ground cork particles to improve the quality of the cast product.
In contrast, the present allows one to inhibit the formation of voids and fissures in cast articles and particularly gravity cast-lead or lead alloy articles though formation of pitted surfaces on the mold. The mechanism of how the pitted mold surface inhibits the formation of voids and fissures in the part formed therein is not fully understood. In general the mold surface is pitted through a process such as electronic discharge machining or the like which allows one to control the pitting of the mold surface. The pitting of the mold surface produces tiny voids in the mold surface. The voids are maintained sufficiently small so the molten metal does not flow therein yet at the same time the molten metal flows over the pitted surface and solidifies with a finish that is substantially free of voids and fissures that would normally occur if the mold surface were smooth.